Lost motion control system



April 1l, 1950 w, D, HALL 2,503,259

LOST MOTION CONTROL SYSTEM Filed Oct. 31, 1944 /g/GJ.

Patented Apr. 11, 1950 UNITED STATES PATENT OFFICE LosT MOTION CONTROL SYSTEM william D. Hau, Elkins, w. va.

Application October 31, 1944, Serial No. 561,253

11 claims. (c1. 20o-13s) l This invention relates to control devices and more particularly to thermally operated slipfriction devices. The primary object is the provision of an improved form of slip friction device.

According to this invention, a thermal element is mounted on a movable support and upon heating of the element it moves its support and thereby creates the lost-motion" effect that is a part of the operation of slip friction switches.

This application is a continuation in part of my prior copending application S. N. 347,951, filed July 27, 1940, entitled Control systems. The

devices shown in Figures 1, 2 and 3 of this appli-- cation and the description pertaining to those gures are fully disclosed in said prior copending application. My aforesaid prior copending application became abandoned on November 4, 1948, but the inventions disclosed therein were not abandoned since they are being claimed in my copending application Serial No. 735,983, led March 20, 1947, as well as in this Letters Patent, and in my Letters Patent 2,399,673, entitled Control system, granted May 7, 1946.

In the drawings:

Figures 1, 2, 3 and 4 are respectively sectional views of four forms of the invention; and Figure 5 is an end view of the form shown in Figure 4.

While the system of Figure 1 is very effective for many purposes, it is particularly useful in systems subjected to considerable jarring, and it uses a lost-motion or slip-friction switch having rotary motion instead of linear' motion. In Figure 1, a central rigidly supported shaft 50 is composed of stainless steel. An outer sleeve 5| has a diameter slightly larger than shaft 50 and is arranged to freely slip around the shaft 50. A spring 94 bears downwardly on sleeve 5| and places considerable contact pressure between the sleeve 5| and the shaft 50. Spring 94 does not engage either the arm 52 or bimetal 33 as this spring bears against a portion of sleeve 5| which is in front of the strip 33 and sleeve-arm 52. Spring 94 may be omitted from the construction if desired with good operation, since the sleeve 5| and rod 50 may be provided with a proper amount of friction without the spring 94. The strip 33, I have found, may be rather heavy and one specimen device has a strip 33 approximately one-half inch wide, 0.05 inch thick, and of five inches developed length.

The coiled bimetallic element 33 is composed preferabiy 'of the highest quauty heat withstanding bimetal and has an inner end rigidly bolted or Welded to the sleeve 5|. The outer end of this bimetallic strip carries a contact point 53. A

stationary contact point 54 supported by the rigid block 55 cooperates with contact 53. The sleeve 5| carries an arm 52 which arm is relatively light as compared to the total weight of the sleeve 5|. This relationship may be effected by making the sleeve much longer in a direction parallel to the shaft than the arm 52 in such direction. The arm 52 carries a contact 52a. The stationary contact point 56 is arranged to cooperate with movable contact 52a. Another bimetallic strip 51 may be employed, although this strip can satisfactorily be composed of an ordinary rigid metal as under normal conditions the operation of the system does not depend upon ilexure of this strip. The strip 51 is composed of a thick piece of bimetal and deilects to the dotted line position at a temperature of about -50 F. At normal temperatures it is straight or at least curved downwardly only slightly. The reason for flexure of this strip 51 is that should the temperature go to say 50 F. during a cold winter month and at a time when the heating system is not in operation, the 4bimetal strip 33 will not be overstressed but the strip 51 will move from the path of 33 and the free end 53 thereof can rotate counterclockwise without striking any obstruction. If a strip 51 of rigid ordinary metal is used, it is possible for the ambient temperature to fall so low, 50 F. for example, that strip 33 Will strike strip 51 and uponfur'ther fall in temperature internally stress itseli to such a large extent as to take on permanent deformation. Since it is necessary for the ambient temperature to fall approximately 150 F. after the end of 53 strikes 51 before the strip 33 would be permanently stressed in event strip 51 was of rigid metal, the outer end of strip 33 will touch 51 at room temperatures and exert a slight tension against 51. This small tension will not premanently deform the resilient bimetallic strip 33. Contacts 52a, 56 are therefore closed at ordinary room temperatures, but contacts 53-54 open. The wire 36| is a exible lead and fastens to arm 52; however, the wire does not have any spring action or in any way mechanically exert a force directly upon arm 52; it merely connects electrically thereto.

Upon applying potential to wires 35, 36 while the apparatus is in the initial Off position, only one current path exists, namely: 35|529 56-52a-3S- Heat from resistor 29 affects strip 33 and causes the same to tend to coil up. This will not break the circuit at 52a-56 at this time inasmuch as the friction between and 5| is appreciable and will tend to hold the position shown until a deflnite torque is exerted on the sleeve 5I by the bimetallic strip 33. The contact 53 moves through midair until it strikes contact point 54. During this time, prior to strikingf this contact point, it is clear that strip 33 cannot exert a torque on the sleeve 5I. Finally as resistor 29 gets strip 33 hotter and hotter -the contact 53 moves into engagement with Stationary contact 54 and this engagement closes the motor circuit via the following current path: 35-M-55-54- 53--33-5I-52-36. For a time after this, both the motor M and the igniter I5 operate simultaneously. The time during which the two operate simultaneously is governed by the tension in spring 94. If this spring causes considerable tension -between sleeve 5I and rod 53, the igniter I5 and the motor M will operate simultaneously for a long time. Another method of obtaining a long simultaneous operation of those parts is to have resistor 29 just powerful enough to barely heat strip 33 to the point where the circuit heats strip 33 barely to the point where the circuit between 52a and 56 is broken. Preferably, the tension and/or heating is so arranged so that the motor M and igniter I5 operate simultaneously for the time deemed best for the particular style of burner to which the invention is applied, which in general is about l5 to 30 seconds. As just stated, the igniter l5 and motor M operate simultaneously for a while. lf the fuel ignites, heat will be supplied to strip 33 from the combustion chamber and this strip will continue to flex. Since contact 53 has now struck a rigid obstruction 5d further llexure of the strip will result in rotation of the sleeve 5l against the frictionof stationary shaft 53. Consequently arm 52 will be rotated counterclockwise and contact between 52a and 56 broken. This deenergizes the igniter i5 and resistor 23. Further heating will continue to rotate arm 52 counterclockwise and contacts 53 and 53 will remain in engagement. If the heater becomes rather hot and then the now of fuel ceases, the friction between 5G and 5I will be sufficient to hold arm 52 in the position it had when the name went out. Cooling of 33 will therefore result rst in a counterclockwise rotation of contact point 53, and a quick disengagement of 53 and i, However, such rotation is limited as the free end of strip 33 strikes 5l after rotating clockwise a fraction of an inch. As soon as strip 33 strikes 57 the subsequent ilexure of strip 33 will result in a clockwise rotation of arm 52 with slippage taking place at 5G, 5I. Strip 5l will finally return to a straight position from its high temperature condition and as strip 33 approaches room temperature its contacts 52m-56 will be reclosed. This closure will reclose the igniter circuit I5, reenergize resistor 29, reheat 33 which strip will begin to rotate 53 clockwise with out any slippage taking place at 5G-5I, reclo-e 53-54, restart the motor, and subsequently reopen the circuit to the igniter at ta- 56. Hence an attempt at reignition will be made.

After being placed into operation, when the heating system reaches a predetermined temperature, the bimetallic switch 6I closes to 60 starting an added fan motor 6l that is also energized from wires 35 and 35.

The control system of Figure 2 will now be described in detail. It is shown in section in the drawing and has a shaft 56 fixed at the rear end thereof. Sleeve 5I is arranged to slip over the shaft 50 as the sleeve has a very slightly larger diameter than the shaft. The spring 3d is l0- cated in front of bimetallic strip 33 and presses firmly on sleeve 5I (which obviously extends well in front of strip 33 as sleeve 5| ls sectioned whereas the strip 33 is shown in full view). The arm 52 is fastened electrically and mechanically tol sleeve 5I and extends behind bimetallic strip 33 and carries a contact 52a. The bimetallic strip is arranged to coil up when heated and to uncoil when cooled. A stationary support 61 supports screw 68, the latter carrying on its tip end a contact point 69. Another stationary contact, not electrically connected, is provided at 56. A stationary square bar 66 supports a large movable block 65. A contact point 64 is fastened to the block 65, moreover a piece of electrical insulation extends across block 65 at 65a. An electrical hot-wire igniter I5 has a resistor 29 in series with it. Resistor 29 is arranged to heat strip 33 when energized.

In the off position, arm 52 is initially against 63 and strip 33 has its lower end against 55a. Hence, contacts 63 and 6B are disengaged. When power is applied at 35, 35, current flows as follows: 35-I5-29-61-69-52a-52-36- Hence resistor 29 becomes heated and causes strip 33 to coil up until Contact 63 engages 5t. This causes motor (or valve) M to be energized via the following circuit, 36-52--33-63-63-65- 6B-M-3I-33-9fi-35. For an interval the motor M and igniter l5 will simultaneously operate thus igniting the fuel. Further heating of 33 due to heat from the flame (or 29) will result in further ceiling up of 33. Since block is very heavy, slippage will take place at 5il-5l before 65 will slip. Hence contacts 33-52@ will be broken and arm '52 will move into engagement with 5E. Since 56 is stationary, the slippage will now take place at 65-@3 and as the burner continues to heat, the block will slip along t6 with 63 and Bri maintaining contact. An arm 96 is pivoted near its center at 32.' It carries on its lower end a contact point 33. A complementary stationary contact point El@ connects to Wire A spring Si tends to produce clockwise motion of the arm and thereby normally maintain the contacts 93 and 33 together. When overheating takes place block 65 moves to the left, engages arm 9D, rotates the latter, and breaks the motor circuit at 93, Sil. If spring 3l is omitted the system cannot be restarted without manually resetting arm 9B. With spring el connected, the system will restart automatically when strip 33 cools.

Should the burner satisfactorily ignite and lburn for a long while, then the flame be accidentally extinguished, 63 will immediately drop away from 64 and rotate counterclockwise until it comes into contact with 65a. Strip 33 will tend to further uncoil and reclose 52a--69 thus reenergizing the igniter circuit I5. Heater 29 will reheat 33 thus reclosing 63 and 64 restarting the motor M. Should the flame fail to relight, the heat from 29 will tend to further coil up 33 so as to break the circuit at 52a-I9. This will cause 33 to cool and move into engagement with 65a. Further cooling will take place thus reclosing 52m-B9 and .this will reheat 29 and 33 thereby making another attempt at ignition. As a result, repeated ignition attempts are made. The same holds true in event an original attempt at ignition fails; that is several attempts to ignite will be made if the rst effort fails.

In Figure 3 there is shown an arrangement whereby a mechanical valve may be operated by my novel control system instead of the motor or valve hereinbefore previously illustrated. The

thereof. A pipe 210 has a valve 253 therein whichv has a stopper 254 that under normal conditions presses firmly against the right face of pipe 21| and thereby holds the valve closed. A shaft 250 has a slipping sleeve 25| and a spring 294 cooperating with it as has been previously described in connection with Figures 3 and 4. An arm 252 secured to sleeve 25| has a contact point 252a which normally presses firmly against the stationary contact 256. Current is applied at wires 35 and 36 to room thermostat T and safety switch SS, the latter which may be built like is shown in casing |3 of my prior Patent 2,159,658, May 23, 1939, entitled: Control system. A heating resistor 2|5 is located close to strip 33 for the purpose of heating the latter. A flexible wire 202 leads current to arm 252.

The operation of Figure 3 is described as follows. When thermostat T calls for heat, current immediately flows through heater 2|5, and simultaneously it iiows via the following path: 36-202-252--256-'229-SS-35- The igniteris therefore heated. The heat from heater 2|5 heats bimetallic strip 233 which thereupon moves stopper 254 away from the opening in pipe 21| and admits ow of gas to the elongated burner 240. The igniter 229 will normally ignite this gas and the same will spread across the burner and provide further heating of strip 233. As strip 233 becomes hotter, the stopper 254 will move to the left as far as it can whereupon further tension in strip 233 will result in counterclockwise rotation of arm 252 and breakage of the igniter circuit. The strip 233 will continue to be heated under the inuence of two heat sources namely heater 2|5 and the name. As strip 233 becomes hotter, it will move arm 252 further counterclockwise, by overcoming the friction between sleeve 25| and rod 250 and spring 294. Shouldthe thermostat T cease calling for heat by breaking its circuit, the heater 2|5 will be immediately deenergized. Since strip 233 is heated by the flame and heater 2|5, and the latter source of heat has been cut off, the strip 233 will cool off somewhat, and this will result in no change in position of arm 2-52 at first but will cause the valve 253 and stopper 254 to move to the right. Movement of 254 to the right will either close the valve completely or close it partially. If it only closes it partially, the name will be reduced in size and this will effect further cooling of 233 due to heat generation falling off. In any event the flame will go out, and once stopper 254 has been properly seated the strip 233 will cool further until iinally contact at 252a 256 is reclosed. The apparatus is then ready to be started again upon further call for heat from the thermostat T.

Other operations of the system of Figure 3 include closure of the valve Iupon flame failure. If the burner should ignite satisfactorily and then continue in operation indefinitely or for a long iperiod, whereupon the gas supply should become exhausted, the nrst thing that will happen is a closure of the valve and subsequent reclosure of the igniter contacts 252a-256. If the gas supply is renewed in the meanwhile and begins to exert pressure in pipe 21|, it cannot now Iuntil a substantial time has elapsed from the time it originally stopped, and not until the ignitel has again been energized. When the 6 igniter is reenergized by thermostat T the heater 2|5 will heat strip 233 and reopen the valve.

In Figure 4, another form of the invention is shown in-which the bulb 500 is connected by feed line 50| to the Bourdon tube 502. The feed line 50| is a steel tube having a small hole leading from bulb 500 to the Bourdon tube 502. The steel line 50| is supported by three bearings 503, 504 and 5|3 which are nothing more than supporting members with holes in them large enough for the line 50| to pass therethrough without excessive friction. The three bearings 503, 504 and 5I3 are all stationary. The lower end 5| 4 of Bourdon tube 502 is adapted upon rotating clockwise (see Fig. 5) to :push the arm 5|5 freely about pivot 506 until stop 501 which is xed is engaged. The mercury switch 505 is carried by the arm 5|5 4and has lead wires 503 which may be connected in series with the burner motor of an oil burner. The arm 5|5 is held against 5|4 due to the weight W on the right end of the mercury switch. Another mercury switch 509 is carried by an arm 5|6. Normally when the bulb 500-is cool, the Bourdon tube 502 has contracted, that is tended to coil up, and the end 5|4 is pressed against stop 5|1 while arm 5|6 is pressed against stop 5| I. The mercury switch 509 may be connected in series with the resistor 29 of Figure 4 as well as the electrical igniter. The hookup of the parts may correspond to the hookup of Figure 1 of this application or the hookup of my prior copending application S. N. 492,737, filed June 29, 1943 (now U. S. Patent 2,399,673, dated May 7, 1946 and entitled Control system) except that switch leads 5| 0 connect to a relay which open the igniter when the circuit at 5|0 is closed.

The operation of Figures 4 and 5 is as follows. When the burner is off the parts will assume the position of Figure 5. Upon starting, resistor 29 will heat bulb 500, expanding the liquid therein and rotating the end 5|4 clockwise until it pushes 5|5 sufficiently to rotate the mercury switch 505 to close contacts 508 and start the burner motor which will generate much heat at bulb 500 which will in turn further rotate the Bourdon tube 502 until 5 5 strikes stop 501. The next action will be a counterclockwise rotation of shaft-line 50| thus rotating kmercury switch 509 to break the igniter and resistor 29 circuit at contacts 5|0.

It is noted that during the rotation of arm 5|6, the entire shaft-line 50| and bulb 500 are likewise rotating. After the bulb 500 should reach some high temperature, should the flame be accidentally extinguished, the Bourdon tube 502 would immediately begin to contract and first the free end 5I4 would move counterclockwise thus breaking the circuit at 508 stopping the motor and after still further cooling the free end 5|4 would engage stop 5|1. Subsequent cooling of the bulb 500 would result in rotation of arm 5|6 clockwise until at some low temperature the contacts 5|0 of mercury switch 509 Would be reclosed.

'Ihe arm SIB and bulb 509 must be counterbalanced for best results unless there is enough friction between shaft 50| and the supports that counterbalancing is unnecessary. A suitable counterbalance 5|2 is shown in Figure 5.

I claim to have invented:

1. In a lost-motion device, a stationary supporting means, a rotatable member supported thereby and frictionally engaged therewith, said frictional engagement constituting substantially u the sole force opposing rotation of said member. an expansible and contractable member having one end connected to said rotatable member, means positioned so as to be engaged by the other end of said expansible and contractable member upon change in dimension of the latter to thereby exert a force on said rotatable member, and switch means associated with the lastnamed means and with said other end for changing the energization and deenergization of a circuit upon engagement and disengagement of the said last-named means and said other end.

2. In a lost-motion switch, thermal means including a coil element which coils and uncoils when the thermal means is heated or cooled, a rotatable member supporting one end of said coil, stationary means in frictional engagement with and supporting said rotatable member, said frictional engagement constituting the sole restraining force between said rotatable member and said stationary means, restrainingr means positioned so as to be engaged by the other end of said coil upon limited movement thereof, said restraining means effecting sufcient restraint as to cause said coil to rotate said rotatable member after the coil begins exerting a force on the restraining means, a rst mechanism operated when said coil exerts a force on said restraining means, and a second mechanism operated by the position of said rotatable member resulting from the rotation thereof.

3. In a lost-motion switch, thermal means including a coil which coils and uncoils when its temperature changes, a. contact point rigidly connected with the iirst end of said coil, a rotatable member frictionally supporting the second end of said coil to ,permit rotationthereof against friction as substantially the entire retarding force, a complementary contact point for the first-named contact point, and means supporting said complementary point a short distance away from the first-named point and restraining motion of the complementary point by a greater retarding torque than is necessary to rotate the rotatable member.

4. The combination with a Bourdon tube of a bulb connected with a iirst end of the tube, means mounting said first end for unbiased rotation, and means permitting free motion of the other end of the Bourdon tube for a limited distance, and a. mechanism operated by the position of said free end.

5. The device defined by claim 4 including an additional mechanism operated by said iirst end of said Bourdon tube.

6. The device dened by claim 4 in which said means mounting said rst end for unbiased rotation is a shaft supporting both said bulb and said tube whereby they both rotate together, said shaft dening an opening therethrough connecting the bulb to said tube. n

7. `The device dened by claim 4 in which said means permitting free motion of said other end of the Bourdon tube for a limited distance comprises a stop on one side of the said other end and sa'fd mechanism comprises a switch on the other side, said switch constituting means for.

preventing further motion of said other end after a predetermined motion, the combination being so constructed and arranged with such small friction retarding rotation of the first end 'of said tube that as the Bourdon tube exerts pressure on the switch after further motion has been prevented that the first end of the tube will rotate to tend to relieve such pressure.

8. The device defined by claim l in which said 8... switch means comprises;. a. rotatable element. comprising a mercury tube switch, operated by the said other end of said member to rotate said mercury tube switch.

9. The device defined by claim 2 having in addition means limiting the motion of said rotatable member in both directions to a predetermined distance, stationary supporting means in frictional contact with said restraining means for permitting movement of the restraining means, said movement being retarded by friction, said friction retarding said restraining means being of such magnitude that when said restraining means is at first engaged by said coil that the restraining means will not move but the coil will rotate the rotatable element through said predetermined distance and thereafter further rotation of the coil will move the restraining means.

10. In a lost-motion device, an expansible and contractable member having rst and second ends and tending to move said first end in iirst and second directions in response to expansions and contractions respectively of said member, restraining movement of said first end in said iirst and second directions, a movable element in contact with and driven by said second end, a supporting structure carrying said movable element and retarding the movement thereof to such a small extent that the force applied to said movable element by said second end due to predetermined expansions and contractions of said member will move said movable element, and control means operated by said iirst end for operating a mechanism in a first manner as long as said rst end is tending to move said restraining means in one direction and in another manner as long as said rst end is tending to move in the other direction.

l1. In al lost motion device, an expansible and contractable member having first and second ends, means associated with the first end for permitting limited motion of the first end in a first direction and then restraining further motion of the first end in said iirst direction, a sliding mass driven by the second end of said member, frictional supporting means for the sliding mass for providing frictonal forces against motion of said mass, the forces retarding said mass being sufficiently small that after said iirst end moves said limited distance further substantial deection of said member will. result in sliding of said mass, and control means for operating a mechanism in a manner depending on the position of said iirst end.

12. In lost-motion switching means, iirst and second sliding masses respectively mounted for sliding motion and each including frictional retardation to such sliding with the second mass having considerably greater friction against sliding than the iirst, means for limiting the extent of sliding of the rst of said masses, an expansible and contractable member for driving said sliding masses against their frictional forces which upon expansion and contraction of the member drives the first mass to its limit of sliding and then drives the second mass to relieve further stress in said member, a first switching means to hold open a circuit when the first mass is tending to slide in one direction and to hold closed the circuit when the iirst mass is tending to slide in the other direction, and a second switching means to hold open a circuit when the second mass is sliding in one direction and to hold closed such circuit when: the second mass is moving in the other direction.

13. In a lost-motion device, an expansible and contractable member having iirst and second ends arranged to deect relative to each other in n spectively in response to expansions and contractions of said member, means for limiting the extent of motion of said mass within predetermined close limits, additional means cooperating with the second end of said member for permitting the second end to move to relieve stress in the member comprising asecond mass restrained against motion substantially Wholly by friction and to a greater degree than the iirst mass and driven in opposite directions respectively in response to expansions and contractions of said member, whereby in response to expansion of the member the rst mass will slip iirst to the extent of its limited motion and thereafter in response to further expansion the second mass will slip, one of said masses including supporting means for said member to carry the latter, a first mechanism operated in a manner depending on the position of the rst mass, and a second mechanism operated in a manner depending on the direction of motion of the second mass.

14. 'I'he device dened by claim 10 including additional means for controlling a mechanism depending on the position of said movable element.

15. The device defined by claim 14 in which the control means is a valve which is moved to a iirst position when said iirst end is tending to move the restraining means in one direction and which is moved to a second position when said rst end is tending to move in the other direction.

16. In the device defined in claim 4: said means mounting said first end for unbiased rotation comprising a shaft supporting both said bulb and said tube whereby they both rotate together, said shaft defining an opening therethrough connecting the bulb to the tube, said means permitting free motion of the other end of said Bourdon tube for a limited distance comprising a stop on one side of said other end, said mechanism comprising a switch on the other side of said other end, said switch constituting means for preventing further motion of said other end after a predetermined motion, and an additional mechanism controlled by rotation of said shaft, the combination being so constructed and arranged with such small friction retarding rotation of said iirst end of said tube that as the Bourdon tube exerts pressure on the switch after further motion has been prevented that the iirst end of the tube will rotate and operate the. second mechanism as well as tend to relieve said pressure.

17. The device defined in claim 11, in which said expansible and contractable member comprises a spiraled bimetallic strip, in which said sliding mass comprises a rotatable element supporting the inner end of said spiraled bimetallic strip, and in which said control means for operating a mechanism includes an electric switch actuated by motion of said iirst end.

WILLIAMD. HALL.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,051,525 Theobald Jan. 28, 1913 1,730,831 Shivers Oct. 8, 1929 2,027,071 Toy Jan. 7, 1936 2,043,441 McCabe June 9, 1936 2,210,922 Joesting Aug. 13, 1940 UNITED STATES PATENT OFFICE CERTIFICATE OE CORRECTION Peten-E; No., 2, 503, 25.9

It is hereby certified that error appears in the printed specification of the above numbered patent .requiring correction and that the said Letters Patent should readas corrected below.

- V l Co'lumn 8, line 2i, Claim lO, after the Word and comme, "member,' insert e restraining means no Signed and, sealed this 31st da;r oi May 1960.

(SEAL) attest: Y

KAEL TE, MEINE ROBERT C. WATSON .ttesting Ocer i n Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No., 2,503,259 April ll, lQEO Villiam D., Hall It is hereby certified that error appears in the printed specification of the above numbered patent .requiring yconvection and that the said Letters Patent should Ieadas corrected below.

Column 8, line 2l, Claim lO, after the Word and Comma, "member," inset e restraining means Signed and sealed this 31st day of May 1960 (SEAL) jttest:

KARL H., MEINE Y ROBERT C. WATSON Ltiesting Gflcei Commissioner of Patents 

